Some prefer the shaped Toto softclose seats, and some prefer the flater seats.
Any elongated seat will work with the EL bowl.
Are you sure you are sitting back where the seat is wider, or are you sitting near the front where it narrows?

I "discovered" that if you sit too close to the front of the Toto seat it IS uncomfortable. I did sit too close to the front at first because I was used to a smaller round toilet in that bathroom. I found that if I sit a little closer to the back, the Toto Softclose seat is more comfortable than my old Mayfair or Bemis.
Tom
& Remodel, 1992-2005